If the mean of five observations `x ,\ x+2,\ x+4,\ x+6,\ x+8\ i s\ 11 ,` then the mean of first three observations is 9 (b) 11 (c) 13 (d) none of these

Explanation

Given data:

`=>x,x+2,x+4,x+6,x+8`

`=>(x+(x+2)+(x+4)+(x+6)+(x+8))/5`
​
`⇒(5x+20)/5`

​`=>11`

`⇒x=7`

Substitute for x in each of the last three terms:

`=> (x + 4) + (x + 6) + (x + 8)`

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